Spatial noise cancellation inside cars: Performance analysis and experimental results

A loudspeaker array is a key component in active noise cancellation (ANC) systems. Most in-car ANC systems utilize the car’s own integrated loudspeakers to cancel the noise due to engine and other sources. In this paper, we evaluate the integrated loudspeakers’ noise cancelling capabilities by analyzing the in-car noise field and the loudspeaker responses. We show that the average noise power in a spatial region can be expressed using a series of coefficients, and that the noise field can be decomposed into several basis noise patterns. Through analysing the measurements in a car, we show that the car’s built-in loudspeakers are capable of attenuating the driving noise by up to 30 dB for frequencies up to 500 Hz within a spherical region of 10 cm radius

Noise cancellation over spatial regions using adaptive wave domain processing

This paper proposes wave-domain adaptive processing for noise cancellation within a large spatial region. We use fundamental solutions of the Helmholtz wave-equation as basis functions to express the noise field over a spatial region and show the wave-domain processing directly on the decomposition coefficients to control the entire region. A feedback control system is implemented, where only a single microphone array is placed at the boundary of the control region to measure the residual signals, and a loudspeaker array is used to generate the anti-noise signals. We develop the adaptive wave-domain filtered-x least mean square algorithm. Simulation results show that using the proposed method the noise over the entire control region can be significantly reduced with fast convergence in both free-field and reverberant environmentsThanks to Australian Research Councils Discovery Projects funding scheme (project no. DP140103412). The work of J. Zhang was sponsored by the China Scholarship Council with the Australian National University

Spatial Noise-Field Control With Online Secondary Path Modeling: A Wave-Domain Approach

Due to strong interchannel interference in multichannel active noise control (ANC), there are fundamental problems associated with the filter adaptation and online secondary path modeling remains a major challenge. This paper proposes a wave-domain adaptation algorithm for multichannel ANC with online secondary path modelling to cancel tonal noise over an extended region of two-dimensional plane in a reverberant room. The design is based on exploiting the diagonal-dominance property of the secondary path in the wave domain. The proposed wave-domain secondary path model is applicable to both concentric and nonconcentric circular loudspeakers and microphone array placement, and is also robust against array positioning errors. Normalized least mean squares-type algorithms are adopted for adaptive feedback control. Computational complexity is analyzed and compared with the conventional time-domain and frequency-domain multichannel ANCs. Through simulation-based verification in comparison with existing methods, the proposed algorithm demonstrates more efficient adaptation with low-level auxiliary noise.DP14010341

Uncommon Sounds in Common Spaces

Discovering uncommon sounds in common spaces provides a mechanism for breaking patterns of predictable listening. Unexpected sonic events draw listeners’ attention and further sustain interest when nurtured with sensitive intentionality. I contend that through subtle yet powerful shifts of everyday behavior it is possible to facilitate diverse and meaningful shared aural experiences. My research investigates what perspectives and relationships might be forged through such an expansion of listening inside of entrance foyers, corridors and staircases in urban multi-storey buildings. I explore this dynamic using microphones, loudspeakers and radio transmission across a series of site-responsive sound installations. These sonic and spatial interventions encourage varied modalities of listening and participation. In this context, my intention is not so much to create new sounds; rather, it is to amplify what is occurring in the environment

Reactive control of subsonic axial fan noise in a duct

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Silencing cortical activity during sound-localization training impairs auditory perceptual learning

The brain has a remarkable capacity to adapt to changes in sensory inputs and to learn from experience. However, the neural circuits responsible for this flexible processing remain poorly understood. Using optogenetic silencing of ArchT-expressing neurons in adult ferrets, we show that within-trial activity in primary auditory cortex (A1) is required for training-dependent recovery in sound-localization accuracy following monaural deprivation. Because localization accuracy under normal-hearing conditions was unaffected, this highlights a specific role for cortical activity in learning. A1-dependent plasticity appears to leave a memory trace that can be retrieved, facilitating adaptation during a second period of monaural deprivation. However, in ferrets in which learning was initially disrupted by perturbing A1 activity, subsequent optogenetic suppression during training no longer affected localization accuracy when one ear was occluded. After the initial learning phase, the reweighting of spatial cues that primarily underpins this plasticity may therefore occur in A1 target neurons

Theory and Design of Feasible Active Noise Control Systems for 3D Regions

This thesis advances Active Noise Control (ANC) over three-dimensional (3D) space using feasible loudspeaker and microphone array systems. By definition, ANC reduces unwanted acoustic noise by generating an anti-noise signal(s) from secondary loudspeakers. The concept of spatial ANC aims to reduce unwanted acoustic noise over a continuous 3D region, by utilizing multiple microphones and multiple secondary loudspeakers to create a large-sized quiet zone for listeners in three-dimensional space. However, existing spatial ANC techniques are usually impractical and difficult to implement due to their strict hardware requirements and high computation complexity. Therefore, this thesis explores various aspects of spatial ANC, seeking algorithms and techniques to promote the reliability and feasibility of ANC over space in real-life applications. The spherical harmonic analysis technique is introduced as the basis of conventional spatial ANC systems. This technique provides an accurate representation of a given spatial sound field using higher-order microphone (spherical microphone array) recordings. Hence, the residual noise field in a spatial ANC system can be effectively captured spatially by applying the spherical harmonic technique. Incorporating conventional spatial ANC methods, we developed a series of algorithms and methods that optimize conventional methods regarding array geometries and ANC algorithms, towards improving the feasibility of a conventional spatial ANC system involving the spherical harmonic analysis. Overall, motivated by feasible and realistic designs for spatial ANC systems, work included in this thesis mainly solves the three problems of: (i) the impracticality of realizing spherical microphone and loudspeaker arrays, (ii) achieving secondary channel estimation with microphones remote from their desired locations, and (iii) unreasonable delays inherent to frequency domain spatial ANC methods. Based on our work, we have stepped towards achieving a spatial ANC system in a real-world environment for people to enjoy silence in the control region with the reliable usage of resources and algorithms. Several contributions of this work are: (i) designing a 3D spatial ANC system using multiple circular microphone and loudspeaker arrays instead of spherical arrays, (ii) proposing a 3D spatial ANC method with remote microphone technique such that noise reduction over a region is achieved with microphones remote from the region, (iii) proposing a secondary channel estimation method using a moving higher-order microphone such that usage of an error microphone array is not necessary, (iv) deriving a time domain spherical harmonic analysis method for open spherical microphone array recording with less delay than in the frequency domain, and (v) designing a feed-forward adaptive spatial ANC algorithm incorporating the time domain spherical harmonic analysis technique to better minimize the noise in the region of interest

Towards a Practitioner Model of Mobile Music

This practice-based research investigates the mobile paradigm in the context of electronic music, sound and performance; it considers the idea of mobile as a lens through which a new model of electronic music performance can be interrogated. This research explores mobile media devices as tools and modes of artistic expression in everyday contexts and situations. While many of the previous studies have tended to focus upon the design and construction of new hardware and software systems, this research puts performance practice at the centre of its analysis. This research builds a methodological and practical framework that draws upon theories of mobile-mediated aurality, rhetoric on the practice of walking, relational aesthetics, and urban and natural environments as sites for musical performance. The aim is to question the spaces commonly associated with electronic music – where it is situated, listened to and experienced. This thesis concentrates on the creative use of existing systems using generic mobile devices – smartphones, tablets and HD cameras – and commercially available apps. It will describe the development, implementation and evaluation of a self-contained performance system utilising digital signal processing apps and the interconnectivity of an inter-app routing system. This is an area of investigation that other research programmes have not addressed in any depth. This research’s enquiries will be held in dynamic and often unpredictable conditions, from navigating busy streets to the fold down shelf on the back of a train seat, as a solo performer or larger groups of players, working with musicians, nonmusicians and other participants. Along the way, it examines how ubiquitous mobile technology and its total access might promote inclusivity and creativity through the cultural adhesive of mobile media. This research aims to explore how being mobile has unrealised potential to change the methods and experiences of making electronic music, to generate a new kind of performer identity and as a consequence lead towards a practitioner model of mobile music

The instrument in space: The embodiment of music in the machine age

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The body exists in space and time. It moves through cultural spaces and temporal rhythms. In the combination of instantiated actions and environmental conditions a context is created, this through embodiment. In this thesis I will attempt to link definitions of embodiment with the process of creating and performing new sound theatre works that involve live interaction with media technology. I will also examine terms such as inscription or incorporation and their application to processes of learning and memory within a particular context of inter-disciplinary skills. Finally, in the light of this genre, I will approach the problematic of analytical procedures that change the very parameters of embodied knowledge. The term sound theatre could be defined as a shift of play between music, image and text, incorporating elements such as gesture, choreography, audio and visual technology into a compositional dialogue. However this approach demands a re-examination of the spatial and temporal aspects involved in such inter-activity and their consequent relation to the performer. Taking the starting-point of sound and movement within the body of the performer, my research involves investigations into medial extensions of embodiment that have developed through a discourse with machines. This project takes an essentially practical basis for its research in the form of collaborations with musicians and practitioners of media technology towards a creative product. The result is a series of written compositions, each of which examines a different aspect of sound theatre. The valuable exchange that takes place during such a situation of experimentation becomes equally as important as the final product, providing much of the material framework for issues such as terminology and analytical procedures that concern my investigation